1. Field of Endeavor
The present invention relates to a fluid flow engine, and in particular to a turbo engine.
2. Brief Description of the Related Art
A fluid flow engine, in particular a turbo engine, e.g., a gas turbine, a steam turbine, or a compressor, usually has a stator and a rotor which is mounted in the stator to rotate about an axis of rotation. At least one guide vane row is formed on the stator, having a plurality of guide vanes arranged side by side in the circumferential direction with regard to the axis of rotation. The rotor has at least one rotor blade row having a plurality of rotor blades adjacent to one another with regard to the axis of rotation. One guide vane row and one rotor vane row following the former directly downstream with regard to a working gas flow form one step or pressure step of the fluid flow engine. During operation of the fluid flow engine, the rotor blades are exposed to extremely high loads in particular, which has effects on the lifetime of the rotor blades. To improve the economic aspect of the fluid flow engine, it is desirable to prolong the lifetime of the blades, in particular the rotor blades.
Fluid flow engines having the aforementioned features are disclosed in U.S. Pat. No. 411,387, Swiss Patent No. 492,866, U.S. Pat. No. 6,036,438, and German Patent Document number DE 4228879, and offer a comparatively long lifetime of the vanes. Furthermore JP57-018405, JP2001-221006, JP2005-220797 and EP0916812 show fluid flow engines wherein at least the axial distance between the outgoing flow edges of the vanes is varied along a radially measured height of the gas path running between the guide and the rotor vanes.
Many efforts have been made but an optimal design of the guide and rotor vanes has not been found.